Method and apparatus for lenticular liquefaction and aspiration

ABSTRACT

A technique is described for liquefying, or gelifying, a hardened, cataractous lens nucleus and aspirating the same. Heat or heated solution is delivered to the lens nucleus in vivo so that the heat or heated solution is placed in contact with the hardened nucleus in order to heat and liquefy the same. The lens nucleus is irrigated simultaneously with a cooled solution to thereby limit to a very small area where the heat or heated solution is present in the eye. This allows the surgeon precise control over which intraocular anterior segment structures are exposed to the heat or heated solution. The liquefied lens nuclear material is then aspirated from the eye. The above allows the removal of a lens nucleus through a 1 to 2 mm corneal or limbal incision which is smaller than the smallest incision allowable with previously known small incision cataract techniques. The above benefits the patient as it allows small incision cataract removal to be done in a way that is non-traumatic to intraocular structures. The above benefits the surgeon, and the patient, in that it is a relatively straightforward and easy surgical maneuver for the surgeon to perform. This is in stark contrast to current phacoemulsification, which is potentially very traumatic to intraocular structures, and which is a relatively difficult surgical maneuver to perform.

This is a continuation of prior application Ser. No. 08/823,713, filedMar. 25, 1997, now U.S. Pat. No. 6,074,358 which is a division of priorapplication Ser. No. 08/384,655, filed Feb. 6, 1995, now U.S. Pat. No.5,616,120.

BACKGROUND OF THE INVENTION

The present invention relates to cataract surgery and, moreparticularly, to a method and apparatus for liquefying, or gelifying, ahardened, cataractous lens and aspirating the same from an eye. Thismethod and apparatus allows for cataract removal through a very smallincision, in either the peripheral cornea or surgical limbus. Theunequivocal superiority of this method and apparatus compared to presentsmall incision cataract extraction techniques is that it isnon-traumatic to intraocular structures, that it is much easier for thesurgeon to perform, and that it allows for a smaller incision.

The lens of an adult human eye is about 9 millimeters in diameter andabout 5 millimeters thick. A lens capsule, which is the basementmembrane of the lens epithelial cells and which has structuralintegrity, surrounds the lens. The lens, internal to the capsule, iscomprised of a nucleus and a cortex. The cortex is a soft, thin layerwhich surrounds the centrally located nucleus.

The nucleus is comprised of an outer nucleus and an inner nucleus. Theouter nucleus is soft regardless of the age of the patient. The innernucleus is normally soft until approximately the age of 45. After aperson attains this age, however, the inner nucleus becomesprogressively harder. In some instances, the inner nucleus becomes veryhard. When the inner nucleus is soft and relatively elastic, the lensreadily changes shape in order to focus, a process known asaccommodation. As one grows older and the inner nucleus hardens, theability of the lens to accommodate decreases. Glasses can be worn inorder to correct this deficiency. Wearing glasses will not, however,correct the vision of a person who has a significant cataract.

An eye becomes cataractous when the lens becomes opaque. Cataracts causediminished vision. If the degree of opaqueness is significant thecataractous lens may be surgically removed. For many years, the mostprevalent surgical procedure for removing a cataractous lens wasintracapsular extraction. In an intracapsular procedure, the entire lensalong with the capsule is removed. A major drawback with this procedureis that the resulting aphakic (lensless) eye has no capsule. Therefore,because there is no capsule there is no capsular support for a posteriorchamber intraocular lens (IOL).

Extracapsular lens removal has rapidly become the preferred method forcataract removal since the advent of intraocular lens implants. Withthis procedure, the anterior portion of the capsule is cut open so thatthe cataractous lens can be removed. However, the equatorial andposterior portions of the lens capsule are left intact. Once thecataractous lens nucleus and cortex are removed, the implant can beinserted therein. In traditional extracapsular cataract extraction, thelens nucleus is delivered manually. A drawback of this is that arelatively large incision (from 8 mm to 11 mm) must be made in thelimbus in order to remove the cataractous lens. That large of anincision causes a relatively lengthy post-operative healing time and isoften the cause of significant surgically-induced post-operativeastigmatism.

In recognition of the drawbacks of the aforementioned extracapsularprocedure, phacoemulsification was introduced. This technique involvesthe utilization of an irrigation/aspiration handpiece that has anultrasonic tip attached to the distal end thereof. See, for example,U.S. Pat. No. 3,693,613. The ultrasonic tip, which is rather sharp andmade of metal, vibrates approximately 40,000 times per second in orderto break up the lens nucleus into tiny pieces so that these pieces canthen be aspirated from the eye. The advantage of phacoemulsification isthat it allows lens nucleus removal through a relatively small incisionof about 3 mm. The disadvantage, however, is that it has proven to berelatively dangerous since the ultrasonic tip destroys any and alltissue that gets in its way. If the vibrating tip comes into contactwith the cornea, iris, or capsule, it can cause serious and permanentdamage. Moreover, during the break up of the hard nucleus, a chip canbreak off and effectuate a tear in the posterior capsule. Anotherdisadvantage of phacoemulsification is that it requires a very highdegree of skill, concentration and experience on the surgeon's part forit to be performed well on a consistent basis.

Due to the above, cataract surgeons desire a small incision cataractextraction procedure which is inherently safer and easier to performthan phacoemulsification. U.S. Pat. Nos. 4,078,564, 4,135,516, 4,191,176and 5,022,413 suggest an alternative method for liquefying the hardnucleus so that the same can be aspirated from the eye. The patentsdescribe a method of liquefying the cataractous lens by injecting aconcentrated solution of a lens digesting enzyme onto the lens andthereafter removing the enzyme digested lens material. A drawback withthis method is that it takes, at a minimum, 12 to 48 hours for theenzyme to soften the hardened nucleus material. Accordingly, thecataractous lens can not be liquified and simultaneously aspirated fromthe lens capsule. Furthermore, it is not believed that very hard nucleiwould liquefy with this enzyme technique.

Other methods have also been proposed for breaking up the hardenednucleus so that the same can be aspirated. These methods are described,for example, in U.S. Pat. Nos. 4,744,360 and 4,597,388. To Applicant'sknowledge, however, none of these methods has ever been successfullyutilized.

SUMMARY OF THE INVENTION

The present invention is designed to overcome the deficiencies of theprior art discussed above. It is an object of the invention to provide amethod and apparatus for safely liquefying the hardened nucleus of alens, so as to allow its removal by aspiration. This would allow forlens nucleus removal through a very small incision of 1 to 2 mm ineither peripheral cornea or surgical limbus.

In accordance with the illustrative embodiments and demonstratingfeatures of the present invention there is provided a technique forliquefying a hardened nucleus of a cataractous lens based on the findingthat the nucleus can be melted or liquified if heated to an appropriatetemperature. The liquified nucleus can then be aspirated. According tothe invention, a 1 to 2 mm incision is made into either the cornea orlimbus and an opening is made in the anterior lens capsule. A heatedsolution is then delivered to the lens nucleus though the anteriorcapsule opening so that the solution contacts the hardened nucleus inorder to liquify or gelify the same. The lens nucleus is irrigated witha cooled solution while the heated solution is being delivered to thenucleus. This simultaneous cooled solution is provided to limit to avery small area (of from about 1 to 2 mm) where the solution is actuallyhot. This allows the surgeon precise control over what intraocularanterior segment structures are exposed to heat or heated solution. Theonly exposed structures will be lens cortex, nucleus and capsule. Thelens capsule, however, is not structurally damaged when exposed to theheated solution. The liquified nucleus is then aspirated and the lenscortex is removed by standard irrigation/aspiration technology.

As used in this application, the term liquefy is intended to encompassthe concept of gelify or gelifaction. That is, liquefy or liquefactionimplies changing a hardened lens nucleus into a liquid or into a softenough gel-like substance so that it can be aspirated from the eye bystandard aspiration devices.

Other objects, features and advantages will be readily apparent from thefollowing detailed description of a preferred embodiment thereof takenin conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in theaccompanying drawings one form which is presently preferred; it beingunderstood that the invention is not intended to be limited to theprecise arrangements and instrumentalities shown.

FIG. 1 is an elevational view of a lenticular liquefaction andaspiration device constructed in accordance with the principles of thepresent invention, and

FIG. 2 diagrammatically represents a cannula inserted into the lens of ahuman eye.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in detail wherein like reference numeralshave been used in the two figures to designate like elements, there isshown in FIG. 1 a lenticular liquefaction and aspiration deviceconstructed in accordance with the principles of the present inventionand designated generally as 10.

The lenticular device 10 includes a hollow handpiece 12 with a first end14 and a second end 16. An elongated cannula 18 extends from the firstend 14 of the handpiece 12 and terminates in a tip 20. The tip 20 hasthree ports formed therethrough. Three lumens 22, 24, 26 are positionedin the cannula. Each of the lumens has one end communicating with acorresponding port and an opposite end extending into the handpiece 12.

An irrigation tube 28 has one end thereof connected to the lumen 24 andan opposite end connected to a fluid source 30. The fluid source isheated by a heating element (not shown) that can be located within oroutside of the handpiece 12. The heated fluid source 30 supplies heatedfluid through the heated irrigation tube 28 and out of the tip 20 of thecannula 18 via the port associated with the lumen 24. A preferred heatedfluid is a balanced salt solution (BSS). However, a variety of othersolutions that are compatible with the tissue being treated can beutilized. The optimum temperature for the solution is believed to beapproximately 180° F. However, temperatures from about 110° to about215° F. are also believed to liquify the hardened nucleus withoutdamaging the surrounding capsule with the optimal range being about 160°to 200° F. The supply of heated BSS solution can be applied in burstscontrolled by the surgeon in a manner well known in the art.

A cooled solution irrigation tube 32 has one end thereof connected tothe lumen 26 and an opposite end connected to an irrigation supplysource 34. The irrigation supply source supplies fluid through theirrigation tube 32 and out of the tip 20 of the cannula via the portassociated with the lumen 26. Once again, the preferred irrigationsolution is a balanced salt solution. The irrigation supply source ispreferably mounted above the handpiece 12 so that gravity continuouslyfeeds the irrigation solution through the irrigation tube 32 and out ofthe tip 20 of the cannula 18. This irrigation solution should preferablybe chilled pre-operatively as in current phacoemulsification techniques,or may be cooled intra-operatively. The preferred temperature for thecooled solution is believed to be approximately 40° F., although theoptimal temperature will vary depending on the temperature of the heatedsolution and the configuration of the tip 20.

An aspiration tube 36 has one end connected to the lumen 22 and theopposite end connected to a vacuum source 37. The vacuum source 37causes the lens material and the BSS to be aspirated from the lensthrough the tip 20 of the cannula via the port associated with the lumen24. The liquified lens material is disposed of by means well known inthe art. It should be noted that all of the above operations arepreferably controlled through a controller circuit 38.

To facilitate an understanding of the principles associated with theforegoing arrangement, its operation will now be briefly described.Referring to FIG. 2, a human eye 40 is shown which includes acataractous lens nucleus 42. As is well known, the nucleus 42 issurrounded by a cortex. The lens nucleus 42 is further encompassed by alens capsule 44. A small incision 46 is made in the cornea 48, or in thelimbus 54, to allow the tip 20 of the cannula 18 to be inserted therein.An opening 47 is made in the lens capsule. The cannula 18 is passedthrough anterior chamber 50 and through the opening 47 in the lenscapsule 44. Accordingly, the tip 20 of the cannula is placed in contactwith the cataractous lens nucleus 42.

A cooled solution, preferably BSS, is fed through the irrigation tube32, through the lumen 26 and out the corresponding port in the tip 20 ofthe cannula 18. The flow from the irrigation source 34 is controlled bythe surgeon in a manner well known in the art (e.g. a foot actuated flowcontrol switch).

Heated BSS is fed through the tube 28, through the lumen 24 and out thetip 20. The only portion of the eye that contacts the tip 20 when theheated BSS is being emitted therefrom is the cataractous lens nucleus42. Upon contact with the heated BSS, the cataractous lens rapidlyliquifies. The cooled BSS from the irrigation tube 32 rapidly cools theheated BSS so that the cornea 48, the iris 52 and the zonules 53 willnot be exposed to heated BSS. Accordingly, thermal damage to any of theaforementioned structures will be avoided.

The liquified lens and the BSS are aspirated through the lumen 22 andthrough the aspirating tube 36 when the vacuum source 37 is activated ina manner well known in the art such as through the use of a foot pedal.The aspiration and the irrigation of the lens take place simultaneously.Furthermore, it should be pointed out that the aspiration takes placesubstantially throughout the procedure. That is, it is believed that itis not necessary nor desirable to liquify the entire lens nucleus beforeaspirating the same. Rather, as a portion of the lens nucleus isliquefied by the heated solution, it is irrigated by the cooled solutionand aspirated. This process continues until the entire lens nucleus hasbeen liquified and aspirated. Once the lens nucleus and cortex areevacuated from the lens capsule 44, an intraocular lens implant can beinserted through a small enlargement of the incision 46 and the opening47 in the lens capsule 44.

Experiment 1

A cataractous lens was removed from a 56 year old patient via anextracapsular procedure. The hardened lens nucleus was placed in aspecimen container. A solution of BSS was heated in a cup toapproximately 180° F. The solution was drawn into a 5 cc syringe. With a25 gauge needle, the heated solution was injected into a portion of thelens nucleus. The portion of the lens nucleus contacted by the heatedBSS immediately liquified. In addition, the lens nucleus, which wasoriginally a dark yellow, became clear upon liquefaction. The resultantliquid was clear, not yellow. The BSS was allowed to cool to atemperature under 180° F., but still hot. Injection of this cooler BSSinto the lens nucleus turned it into a soft gummy gel that was lightgrey in color. That is, it changed from a yellow solid mass to a lightgrey gel. The resultant gel was of a soft enough nature that it could beaspirated from the eye with standard irrigation/aspiration technology.

Experiment 2

A cataractous lens was removed from an 80 year old patient via anextracapsular procedure. The hardened, brunescent lens nucleus wastreated with a solution of BSS that was heated to approximately 180° F.The nucleus instantaneously liquified. Next, a piece of the anteriorcapsule was contacted with BSS solution at approximately 180° F. Aninspection of the capsule under operating room microscope (Zeiss)magnification indicated no obvious structural damage to the same.

Although the present invention has been particularly described as amethod and apparatus for lenticular liquefaction and aspiration for thepurpose of removing a hardened lens nucleus and thereafter replacing thesame with an intraocular implant, it is contemplated that the inventionmay have broader implications. By way of example and not limitation andas a direct result of the small capsulotomy size allowed by use of thepresent invention, it may be possible to develop a methodology to killall lens epithelial cells and remove them at the time of cataractsurgery, thus preventing post-operative lens capsule opacification.Furthermore, a malleable, injectable gel-like IOL, could be insertedthrough the 1 to 2 mm anterior capsulotomy resulting from the lenticularliquefaction and aspiration according to the invention. This wouldprovide the patient with an almost completely intact capsule (anterior,equatorial and posterior) at the end of surgery that would not opacifyafter surgery, and that would be comprised of the clear, malleablegel-like IOL. The end result of that surgery would be a clear lens thataccommodates. This would simulate a state very close to the natural lensprior to the onset of either cataract or presbyopia. Current cataractextraction techniques require too large of an anterior capsulotomy toallow the above to occur.

The above surgery could become a refractive surgical procedure for thetreatment of presbyopia; wherein the surgery would be done to remove thelens simply because it is getting too hardened to accommodate properly,even when it is not cataractous.

As indicated above, the heated solution delivered to a yellowed,cataractous lens changed the lens color dramatically from a yellow to aclear liquid, or to a light grey gel. (A non-cataractous lens normallyhas a light grey hue.) As a result, the possibility exists of being ableto deliver heat or heated solution to the lens to clarify it, to removethe opacity, without having to remove the lens from the eye.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof andaccordingly reference should be made to the appended claims rather thanto the foregoing specification as indicating the scope of the invention.

What is claimed is:
 1. In a method for treating cataracts in vivo byliquefying a cataractous lens nucleus and aspirating the same whereinthe improvement comprises liquefying said lens nucleus by heating thesame to a temperature of about 110° F. to about 215° F. by delivering afluid to the lens which has been heated in a fluid delivery system. 2.The method of claim 1 wherein said fluid is a saline solution.
 3. In amethod for treating cataracts in vivo by liquefying a cataractous lensnucleus and aspirating the same from within a surrounding lens capsulecomprising the steps of: delivering a fluid which has been heated in afluid delivery system to a temperature in the range of about 110° F. to215° F. directly into said lens nucleus in order to liquify the same;irrigating said lens nucleus, and aspirating said liquified lens nucleuswhile continuing to irrigate the same.
 4. The method of claim 3 whereinsaid fluid is comprised of a saline solution.
 5. The method of claim 3further including effectuating an opening in said lens capsule, saidheated fluid being delivered into said opening and said liquified lensnucleus being aspirated out of said opening.
 6. The method of claim 3wherein said liquified lens nucleus is irrigated with a cooled solutionso that said lens nucleus and said heated fluid are rapidly cooled. 7.In a method for treating a cataractous lens in vivo by liquefying ahardened nucleus of a cataractous lens and aspirating the same from asurrounding lens capsule comprising the steps of: effectuating anopening in said lens capsule; delivering a fluid which has been heatedin a fluid delivery system to a temperature in the range of about 110°F. to 215° F. through said opening so that said heated solution comesinto contact with said hardened nucleus in order to liquify the same;irrigating said lens nucleus with a cooled solution while carrying outthe heated solution delivery step, and aspirating said liquified nucleuswhile continuing to irrigate the same.
 8. The method of claim 7 whereinsaid heated solution is comprised of a balanced salt solution.
 9. In amethod for treating cataracts in vivo by liquefying a cataractous lensnucleus and aspirating the same wherein the improvement comprisescontacting said lens nucleus with a fluid having a temperature of about110° F. to about 215° F. that has been heated in a fluid deliverysystem.
 10. The method of claim 9 wherein said fluid is comprised of asaline solution.